Disputable issues, however, remained unsettled yet, the source says

VIENNA, July 2. /TASS/. Ministerial talks of Iran and the six world powers — Russia, the United States, Britain, France, China and Germany — (the P5+1 group), which were held in the Austrian capital of Vienna on Thursday, have set an optimistic tone, a high-ranking diplomatic source at the Iranian delegation told TASS.

"I cannot speak about a colossal breakthrough yet but we have a very positive frame of mind tonight," he said noting that disputable issues had remained unsettled yet.

"But we are certain that given a political will of both sides they can be settled," he said. "And there is such a will as we understand."